On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 429 
The teeth comprised in this species vary greatly in form. There is no 
evidence that there was more than one tooth in each ramus of the upper jaw, 
whilst in those of the lower one there were two, probably three, to each. The 
teeth in the upper jaw were more or less triangular in outline, somewhat 
flattened anteriorly, with a strong ridge extending from the posterior or apical 
extremity towards the anterior margin. Greatest length 1-4 inches, width across 
anterior surface ‘8 of an inch. A transverse section across the tooth exhibits 
a sigmoidal curvature along its surface ;a strong ridge occupies half the surface 
nearest to the median line; the remaining portion being depressed and concave. 
The surface is uniformly punctate and a number of imbrications extend across 
its surface parallel with the anterior margin. Anterior margin sigmoidally 
curved, bending with a convex line from the median antero-lateral angle 
towards the opposite one, which is considerably extended and acutely pointed; 
median lateral margin slightly convex; opposite or postero-lateral margin for 
two-thirds its length straight, it then makes a flexure inwards, and with the 
ridge of the crown forms an enrolled beak-like posterior termination, the 
latter being thick and tumid. The base appears to conform generally with the 
crown in outline; it is thin anteriorly and increases in thickness and strength 
posteriorly. Its structure is open and porous with a coating of enamel on the 
crown. 
Taking the number of upper teeth hitherto found, about one half of them 
answer to the above description, whilst the remaining half are reversed. They 
appear to have been connected with each other along the median lateral margin 
by a ligament or otherwise, one attached to each ramus of the jaw. This is 
rendered probable from the fact that such an arrangement would fit and correspond 
with the form of the opposing teeth of the lower jaw ; the high convex ridge 
of the upper tooth would be in contact with the hollow concave portion of the 
teeth of the lower jaw, whilst the convex part of the lower teeth fitted to the 
concave of those of the upper series. 
Lower jaw: teeth differ considerably from those of upper jaw. The two 
central teeth were connected by their internal lateral margins over the median 
line of the lower jaws, the opposite or external lateral margins being connected 
with one, probably two posterior teeth on each ramus of the jaw. The pos- 
terior teeth are quadrilateral, the sides nearly or quite straight, °6 inch in 
length, *8 inch broad in front, and about half that width behind. Crown antero- 
posteriorly round and convex, laterally depressed and concave from the external 
margin to one-third the breadth of the crown. Remaining two-thirds con- 
stitutes a broad deeply convex ridge extending the whole length of the tooth. 
Surface enamelled, granulo-punctate, with a number of transverse equidistant 
sulci, and intermediate ridges extending parallel with the anterior margin; in 
some teeth they are almost obliterated by attrition presenting a simple smooth 
